Fighting fires on tall buildings

Fires in tall buildings over the years have led to many improvements in designs that prevent them from starting or from taking hold, and then if they do, to slow down their spread. Thankfully they are very rare. Existing technology is also very limiting. Ground-based fire appliances can only rescue people from lower floors and can only spray water onto a few floors above that. Fire extinguishers and internal sprinkler systems can obviously help put fires out or slow them spreading if they are actually present and if a few people are willing to take risks. That there were none in Grenfell Tower is simply beyond comprehension. Negligence, incompetence and complacency don’t begin to cover what needs to be said.

However brave firefighters are, and nobody doubts their bravery, they will need better tools to do the job, they are simply not equipped to fight fires in skyscrapers such as we just had. People should not die if there are potential solutions. Some are feasible now, but I am not aware of their use.

External fires such as the Grenfell Tower fire in London recently can’t be fought fully by either internal sprinklers or ground-based hoses. We need new techniques capable of dealing with such fires. A quick googling on future fire fighting is surprisingly disappointing. Even googling future firefighting doesn’t turn up much. Most is about fancy new imaging kit or protective uniforms with embedded sensors. All great stuff, but it won’t stop another Grenfell. I’m no expert in this field, so maybe I just haven’t used the right search terms, but it shouldn’t be as easy as it is to think up solutions that are not already in use. Maybe there are good reasons why the following are not in conspicuous use yet, but I can’t think of any. None of what follows is rocket science.

Water tanks on roofs could be attached to tubing around the perimeter of the building roof, and remotely operable valves could then be used by ground crews to release water in curtains down a side of the building. Obviously capacity is finite, but after initial quenching, continuous water flow from the roof would help, however little. Large tanks could be installed if none are present to add safety to existing building with poor cladding.

A way of getting firefighting kit high up is to use the platforms provided for window cleaning. They could be lowered to below the fire and fire pumps could be put on them, or at least anchorages for steerable hoses. This does not need firefighters to be on them, they could stay below. Clearly, roof kit might eventually fail and wires might break, but meanwhile they could help alleviate the problem and buy time at the very least. If firefighter lives are not put at risk to do it, there is little penalty.

External sprinkler tubes could also be fitted that could be connected to water supplies just below and external fire. This might buy one of two floors of relative safety above and greatly reduce smoke from outside. They don’t even need to have sophisticated nozzles. All they need to do to be useful is to spray some water on some of the external fire. Even if sub-optimal, they would buy a little time.

Drones offer one potential assistance route. Two types are relevant. One is very well known already and I would expect is already in use: Conventional drones can carry cameras and other sensors to higher floors to monitor what is happening, offer assisted networking for internal firefighters, offer firefighters alternative views of the action, enable local and accurate positioning systems, and provide computer-enhanced imaging to augmented reality helmets.

Secondly, high power tethered drones could be powered by connected electrics from the ground, so avoiding the battery and power limitations of conventional drones. They could reach high floors and stay there while supporting hoses from the ground or from lower floors, and might even be able to hold pumps if ground pressure can’t be made high enough. These would offer helicopter-type functionality or lifting capacity without having to go back and forth to refill with water or fuel. Cost would be relatively high, but fire departments would not need many.

Once an external wall is made free of fire, drones and window-cleaning platforms could be used in rescues.

Obviously a lot has been written about futuristic imaging, sensing, navigation and bio-sign monitoring for firefighters, as well as deploying robotic firefighters that can work down from roofs, relatively immune to fire and smoke, so I won’t bother repeating here what is already known well. What is apparently lacking sometimes is low-tech kit and making it actually present.

If these systems are already well known but there are good reasons why they don’t feature, then I have wasted your time.

 

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3D printing the highest skyscraper? 600km tall structures may be feasible.

What would you do with a 600km high structure? That would be hundreds of times higher than the highest ever built so far. I think it is feasible. Here I will suggest super-light, super-strong building materials that can substitute for steel and concrete that can be grown up from the base using feasibly high pressures.

I recently proposed a biomimetic technique for printing graphene filaments to make carbon fur (- in this case, for my fictional carbon-obsessed super-heroine Carbon Girl. I am using the Carbon Trio as a nice fun way to illustrate a lot of genuine carbon-related concepts for both civil and military uses, since they could make a good story at some point. Don’t be put off by the fictional setting, the actual concepts are intended to be entirely feasible. Real science makes a better foundation for good science fiction. Anyway, this is the article on how to make carbon filaments, self-organised into fur, and hence her fur coat:)

http://carbondevices.com/2013/07/01/carbon-fur-biokleptic-warmth-and-protection/

Here is the only pic I’ve drawn so far of part of the filament print head face:

Many print heads would be spread out biomimetically over a scalable area as sparsely or densely as needed, just like fur follicles. A strong foundation with this print head on top could feasibly form the base of a very tall vertical column. If the concept as described in the fur link is adapted slightly to print the filaments into a graphene foam medium, (obviously pushed through the space between the follicles that produce the filaments) a very lightweight foam structure with long binding filaments of graphene graphene foam would result, that would essentially grow from the ground up. This could be very strong both in compression and tension, like a very fine-grained reinforced concrete, but with a tiny fraction of the weight. Given the amazing strength of graphene, it could be strong enough for our target 600km. Graphene foam is described here:

Could graphene foam be a future Helium substitute?

Extruding the supporting columns of a skyscraper from the ground up by hydraulically growing reinforced graphene foam would certainly be a challenging project. The highest hydraulic pressures today are around 1400 bar, 1.427 tonnes per sq cm. However, the density of graphene foam with graphene filament reinforcement could be set at any required density from below that of helium (for graphene spheres of 0.014mm with vacuum inside), to that of solid carbon if the spheres are just solid particles with no vacuum core. I haven’t yet calculated the maximum size of hollow graphene spheres that would be able to resist production pressures of 1400 bar. That would determine the overall density of the material and hence the maximum height achievable. However, even solid carbon columns only weigh 227g per metre height per sq cm of cross-section, so even that pressure would allow 6.3km tall solid columns to be hydraulically extruded. Lower densities of foam would give potentially large multiples of that.

This concrete substitute would be nowhere near as strong as basic graphene, but has the advantage that it could be grown.

(The overall listed strength of solid graphene theoretically allows up to 600km tall, which would take you well into space, perfect for launching satellites or space missions such as asteroid mining. But that is almost irrelevant, since graphene will also permit construction of the space elevator, and that solves that problem far better still. Still, space elevators would be very costly so maybe there is a place for super-tall ground-supported structures.)

But let’s look again at the pressures and densities. I think we can do a lot better than 6km. My own proposal a while back suggests how 30km tall structures could be built using graphene tube composite columns structures. I did think we’d be able to grow those.

Super-tall (30km) carbon structures (graphene and nanotube mesh)

We’d need higher pressures to extrude higher than 6km if we extruding solid columns, but these tube-based columns with graphene filament reinforced graphene foam packing would have a far lower density. The print heads in the above diagram were designed to make fur filaments but I think it is possible (though I haven’t yet done it) to redesign the print heads so that they could print the tubular structures needed for our columns. Tricky, but probably possible. The internal column structures are based on what nature uses to make trees, so are also nicely biomimetic. If we can redesign the print heads, then printing low density columns using a composite of filament reinforced foam, in between graphene tubes should work fine, up to heights well above the 30km I originally suggested. An outer low pressure foam layer can be added as the column emerges. It doesn’t have to withstand any significant pressure so can be as light as helium and add the strength needed to prevent column buckling. With the right structure, perhaps the whole 600km can be achieved that way. Certainly the figures look OK superficially, and there’s no hurry. It’s certainly worth more detailed study.